The programs that I wrote for the Kenbak-1 computer fell into the educational category for instructional purposes or into the fun category (sometimes the two were the same).  Examples from the fun group illustrate what the computer could do.


Is it a legitimate date and if so what day of the week did it fall on? This was a good demonstration program because the audience quickly understood what the program did and the answer that the computer gave.  The dates were confined to the 1900s so it was only necessary to input two digits for the year, two for the month, and two digits for the day. The digits were entered in binary coded decimal and the entries were checked for validity. The answer was returned in the lights. Light number zero was not a legitimate date. Light one was Sunday, the first day of the week, etc.  (Most people could tell you, prior to the current year, only two days for which they knew the correct answer. Can you guess what they were?) When I first demonstrated this program publicly, I was surprised that half of the audience did not know the basic rules for the calendar which of course were a part of the program.


I predict your next guess will be. Another good demonstration program. A member of the audience would name a sequence of heads and tails. The computer would try to predict what the person would next choose. Usually the computer won. This was a simple pattern recognition program that required very little history.  The reason that the program worked is that people cannot choose a random pattern.


Three dimensional tic-tac-toe. This was played on a 4 by 4 by 4 board with the machine against a human opponent. For the human it is good to have a plastic sheets marked appropriately. This program took all of the memory in the computer. In fact, the program did not recognize the end of the game; it just kept playing even though there was a row of four completed in some direction.  Because of the large number of moves that must be examined (at the start there are 64 possibilities with up to eleven directions for playing lines), the game was slow, taking about an hour to complete. Input for the player took six bits in the switches and output from the computer was six bits in the lights.


The educational programs were things like find the largest number in a sequence, sort a sequence, or find which digit in a sequence occurred most often.


For the instruction set and the coding sheet, see Instructions.




Copyright by John Blankenbaker